Fasteners / Clamps / Springs

Fasteners - nuts, bolts, screws, washers, etc. this is the stuff that hold things together. The finish of a fastener is critical to its function. Most fasteners are coated to protect against corrosion and to achieve special properties such as controlling the amount of torque required to tighten a threaded fastener.

Clamps & Springs need to be protected against hydrogen embrittlement. This is why zinc flake products are widely used to protect those parts against corrosion.

Fasteners

The automotive industry is the single largest fastener consumer of any industry, using 26 billion parts annually out of the 200 billion produced, or approximately 42% of the industry. This consumption makes the automotive industry a powerful player and trendsetter in the fastener industry. Because fasteners are used on all parts of vehicles, each part requires different tolerances. The auto industry's requirement to fulfil government regulations impacts the mix of products available to fastener manufacturers and finishers. However, the auto makers still demand the same, or higher quality standards to be achieved in part performance, challenging finish makers to come up with better alternatives.

Here are a few examples of Atotech finishes developed for new automotive requirements.

Process Sequence for Clear Zinc plating of steel bolts with TT requirements: Corrolux® 530L, our unique 'integral' lubrication system for zinc finishes, allows for many types of fasteners with different ge-ometries (i.e.: flanges, washers) be plated using the same chemical system and meet the torque tension requirement regardless of geometry and meet or exceed corrosion requirements. The Corrolux® 530L is a Cr(VI)-free finish, which fulfils the demand of Ford S449. Corrolux® 530L consists of a zinc electrolyte, the passivation Tridur® Zn B with Tridur® Enhancer and sealer with integrated lubricant Corrosil® Plus 501L.

Process Sequence for Clear Zinc plating of steel bolts with reduced contact corrosion to magnesium:
The low difference in electrochemical potential between zinc and magnesium makes zinc coatings perfectly suited to magne-sium contact. The sealer also acts to insulate the zinc coating and therefore reduce the contact corrosion of the less noble magnesium, which easily tends to dissolve. The best process combination for this application is our acid zinc Unizinc ACZ with the passivate Unifix® Zn 3-15 L and our reactive inorganic sealer with integrated lubricant Sealer 300 WL, which is approved for Audi TL 194.

Process Sequence for Clear Zinc-Nickel plating of steel bolts with TT requirements:
With increasing demands for higher corrosion protection the use of zinc-nickel on fasteners is steadily increasing. For that application our alkaline Zinni AL 450 system is combined with the trivalent passivate Unifix® Ni/Fe 3-10 L and our reactive inorganic sealer with integrated lubricant Sealer 300 WL 7.

Process Sequence for Zinc-Nickel plating and black Top coat:
A high glossy good looking black finish with extraordinary corrosion protection is achieved by using Zinni AL 450 and Unifix® Ni 3-30 L in combination with our organic top coat Techseal® Black SL 24.

Process Sequence for silver zinc flake coating of steel bolts with TT requirements:
The zinc flake technology is largely embraced by the fastener industry and a variety of other applications due to its special features like the absence of hydrogen embrittlement. By combining the silver base coat Zintek® 200 and our inorganic top coat Zintek® Top LV a multifunctional coating is formed providing outstanding heat loosening properties. This combination is approved for VW TL-245 .

Process Sequence for silver zinc flake coating of steel bolts with constant TT requirements also against different materials (steel, aluminum and Electrocoat):
The combination of Zintek® 200 and Techseal® Silver WL leads to uniform silver surface with excellent stick slip prevention.

Process Sequence for black zinc flake coating of steel bolts with TT requirements:
Atotech's unique black base coat Zintek® 300 B combined with one of Atotech's top coats, like Techseal® Black SL 24 results in an exceptional deep black uniform appearance without any silver shine through and flake off even after handling. Depending on the top coat used, a glossy (Techseal® Black SL 24) or semi-bright look (e.g. Techseal® Black SL 28) can be achieved.

Clamps & Springs

Clamps & Springs need to be protected against hydrogen embrittlement. This is why zinc flake products are widely used to protect those parts against corrosion.

Process Sequence for Silver Zinc Flake Coating of Clamps & Springs
Zintek® 200 together with Techseal® Silver W are used to coat clamps & springs in silver color and protect them from corrosion.

Process Sequence for Black Zinc Flake Coating of Clamps & Springs
Uniform black appearance without any silver shine through and flake off can be achieved by using Zintek® 300 B and
Techseal® Black S.